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Date: Fri, 16 Mar 2001 14:09:38 -0500
From: David Mansfield <lkml@dm.ultramaster.com>
Organization: Ultramaster Group LLC
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To: Pierre Etchemaite <petchema@concept-micro.com>
CC: Jani Jaakkola <jjaakkol@cs.Helsinki.FI>, linux-kernel@vger.kernel.org,
        Jens Axboe <axboe@suse.de>
Subject: Re: [PATCH] fix a bug in ioctl(CDROMREADAUDIO) in cdrom.c in 2.2
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Pierre Etchemaite wrote:
> 
> Le 14-Mar-2001, Jani Jaakkola ?crivait :
> >
> > Using ioctl(CDROMREADAUDIO) with nframes argument being larger than 8 and
> > not divisible by 8 causes kernel to read and return more audio data than
> > was requested. This is bad since it clobbers up processes memory
> > (I noticed this when my patched cdparanoia segfaulted).
> 
> Same thing for 2.4.2.
> 
> Is my allocation loop "over engineering", or just plain bad thing to do ?
> 

I've been running this (or close: my version tries 8 frames, then jumps
immediately to 1, without trying 4 and 2 in between if the kmalloc
fails) since it was changed.  Without such a patch, my CDDA read speed
drops to 25% the original rate.  You also have the fix that started the
thread!

Jens (cdrom maintainer) said he was working on a more elegant solution,
but to me, such a simple fix as yours should go in the kernel in the
meantime.  Jens?

-- 
David Mansfield                                           (718) 963-2020
david@ultramaster.com
Ultramaster Group, LLC                               www.ultramaster.com
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